Citizen Scientists Help Confirm Giant Exoplanet Discovery

Backyard astronomers wielding personal telescopes across 10 countries played a crucial role in confirming the existence of TOI-4465 b, a massive gas giant located 400 light-years from Earth.

The international collaboration demonstrates how citizen scientists can contribute directly to cutting-edge astronomical research, filling observational gaps that even professional observatories struggle to cover.

The discovery, published in The Astronomical Journal, required an extraordinary coordination effort spanning 14 countries. The challenge? Catching a planetary transit that occurs only once every 102 days—roughly three times per year—and lasts about 12 hours each time.

Racing Against Time and Weather

NASA’s Transiting Exoplanet Survey Satellite (TESS) first spotted TOI-4465 b as a possible single-transit event when the planet briefly passed in front of its host star. But confirming the discovery required observing at least one additional transit—a logistical nightmare given the planet’s extended orbital period.

“The observational windows are extremely limited. Each transit lasts about 12 hours, but it is incredibly rare to get 12 full hours of dark, clear skies in one location,” explained lead author Zahra Essack, a postdoctoral fellow at the University of New Mexico. Weather patterns, telescope availability, and the need for continuous coverage made the task even more daunting.

The solution involved coordinating 24 citizen scientists equipped with personal telescopes, supported by professional astronomers and established observatories. This global network provided the continuous coverage needed to capture the planet’s elusive transit.

A Dense, Temperate Giant

TOI-4465 b represents a fascinating example of planetary diversity in our galaxy. The confirmed measurements reveal a world with distinctive characteristics:

• Size: 25% larger in radius than Jupiter
• Mass: Nearly six times Jupiter’s mass
• Density: Almost three times denser than Jupiter
• Temperature: Ranges from 375-478 K (200-400°F) due to its mildly elliptical orbit

These properties place TOI-4465 b in a relatively underexplored region of planetary characteristics—large, massive, dense, and temperate. Such long-period giants serve as important bridges between the extreme hot Jupiters that orbit very close to their stars and the cold gas giants in our own solar system.

Infrastructure Behind the Discovery

The successful collaboration relied on several key programs that enabled seamless coordination between professional and amateur astronomers. The Unistellar Citizen Science Network provided standardized equipment and data processing capabilities, while the TESS Follow-up Observing Program Sub Group 1 (TFOP SG1) offered a global coordination framework.

“What makes this collaboration effective is the infrastructure behind it,” Essack noted. The TESS Single Transit Planet Candidate (TSTPC) Working Group, led by UNM Assistant Professor Diana Dragomir, brought together the detection and follow-up expertise necessary for these challenging observations.

Professional astronomers, including students, contributed supporting photometric observations that measured changes in the star’s brightness as the planet passed in front of it. This combination of citizen science enthusiasm and professional expertise proved essential for the discovery’s success.

Filling Critical Gaps

Long-period exoplanets like TOI-4465 b remain underrepresented in current planetary catalogs precisely because they’re so difficult to detect and confirm. Limited observational opportunities and resource constraints mean that planets with orbital periods longer than 100 days often slip through the cracks of traditional discovery methods.

“Studying these long-period planets gives us insights into how planetary systems form and evolve under more moderate conditions,” Essack emphasized. These worlds offer a window into planetary formation processes that occur at greater distances from their host stars, where conditions more closely resemble those in our outer solar system.

Future Atmospheric Studies

TOI-4465 b’s combination of large size and relatively cool temperatures makes it an ideal target for future atmospheric studies using advanced telescopes like the James Webb Space Telescope (JWST). The planet ranks among the best long-period exoplanets available for emission spectroscopy studies, which could reveal detailed information about its atmospheric composition and structure.

This discovery represents the sixth installment from the Giant Outer Transiting Exoplanet Mass (GOT ‘EM) survey, which aims to characterize long-period transiting giant planets through coordinated follow-up observations. As citizen science networks continue to expand and professional-amateur collaborations become more sophisticated, discoveries like TOI-4465 b demonstrate the power of global cooperation in astronomical research.

The success underscores how passionate astronomy enthusiasts can play direct roles in frontier scientific research, expanding our understanding of distant worlds while bridging the gap between professional observatories and clear skies around the globe.